Piezoelectric ESWL of ureteric stones. Influence of the site and dimensions of the stones on treatment modalities and performances.

Objective: To evaluate the influence of the site and dimensions of ureteric stones on the modalities and performances of in situ piezoelectric extraco rporeal shockwave lithotripsy (ESWL). Material and Methods: A population of 385 patients with solitary radiopaque ureteric stones was analysed. The long axis of these stones (211 (55%) lum bar 38 (10%) iliac and 136 (35%) pelvic stones) ranged from 5 to 21 mm (mea n = 8.2 mm). The initial shock wave frequency was 4/s. Lumbar stones were t reated in the dorsal supine position under diazanalgesia and pelvic stones were treated in the ventral supine position without systematic sedation. Th e influence of wave frequency (1 versus 4/s) on the level of sedation and t herapeutic performances was studied on 146 patients with lumbar (n=92) or p elvic stones (n=54), The results were evaluated after only one ESWL session and were analysed statistically by Student's test and Fisher test. Results: The overall complete success rate was 74%, Iliac stones were chara cterized by significantly (p<0.05) lower (61%) performances. The results we re inversely proportional to the size of the stones, as the complete succes s rate was only 25% for stones >12 mm. For lumbar stones, a lower frequency allowed a very significant reduction (p<0.0001) of the level of sedation r equired without affecting the performance. For pelvic stones, a low frequen cy significantly (p<0.05) limited the efficacy of ESWL, especially for ston es >8 mm (27% of complete successes). Conclusion: In situ piezoelectric ESWL allows effective management of most ureteric stones with of long axis between 5 and 10 mm. In the context of ou tpatient treatment, however; this approach requires modulation of the shock wave frequency according to the site of the stone. Another therapeutic app roach, particularly endoscopy, should be considered for very large stones.